Venetian blind



July 21, 1953V l.. Rf BucHER- ET AL VENETIAN BLIND Filed Jan. 24, 1952 MC mw. Q. N w

Patented July 21, 19513 UNITED STATES VENETIAN BLIND LeonV R. Bucher and Omar K. Skiver, Riverside,

Calif., assignors to Hunter Douglas Corporation, Riverside, Calif., a corporation of Delaware Application January 24, 1952, Serial No. 267,952

Z Claims. (Cl. 1GO-173) The present invention relates to Venetia blinds, and more particularly to a new and improved type of ,slat Whichisso constructed and arranged as to permit the blind to be closed more tightly than has heretofore been possible, with adjoining slats in actual contact with another. The full-closure blind of the present invention thus makes itpossible to darken a room to an extremely low level of illumination, even in midday, and is therefore ideally suited for use in school classrooms or auditoriums, to permit full utilization of all the visual aids employed in present day teaching methods which require room darkening, such as motion pictures, slides, television, and the like. The present invention provides the optimum conditions for visual aid teaching, inasmuch as it not only darkens the room for projection purposes, butl at thesame time spreads a diffused, uniformly distributed, illumination of very low intensity over the entire room, of the order of 1/2 foot-candle or less for a classroom of average size and modern construction, which is just suicient for note-taking purposes.

Inl a conventional blind, the crowned sheet metal slats are prevented fromv closing tightly together by the lift cords, which pass through cord holes inthe slats.v The cordvlimits the angle to which the slat can be tilted, owing to the fact that in the extreme tilted position of the slat, the cord engages one end of the cord hole and the opposite outer edge of the slat. Thus, there is a gap left between the bottom edge of one slat and the top surface of the next lower surface, of the same width as the thickness of the cord. Light leaking through these gaps'between slats prevents the conventional blind from darkening a room suiciently for projection purposes.

In the present invention, the slats are notched in one edge along side the cord hole, so that in the extreme tilted position of the slat, the cord engages the bottom of the notch and the top end of the cord hole. However, the bottom edge of the slat on either side of thenotch extends further down toward the slat below by a distance equal to the depth of the notch. Owing to the curvature of the downwardly concave slat, the direction in which the bottom edge of the slat extends is directly toward the slat below. f Hence, the gap between the slats when the blind is closed is materially reduced, and maybe eliminated altogether if the notch is made somewhat deeper than thethickness of the cord. Better closure is also obtained if the notch is made wider than the cross bars of the ladder tape, and thel cord hole is offset laterally from the center-line of the slat to the side opposite the notch, which permits the slat to-drop down slightly in the fully tilted position', toward the slat below.

The present invention can ralso be used advantageously wherever it may be necessary or desirable to darken a room to an extremely low level of illumination, as inlhospitals, hotel rooms,

, f 2 f bedrooms, etc., and the primary object of the invention, therefore is to provide a Venetian blind which can be completely: closed to exclude substantially all of the light entering a window, and which isV capable of darkening ak room to an illumination level substantially below that obtained with conventional blinds.

Another object is lto provide a blind giving a relatively uniform` distribution of light at all levels of intensity, and one that diiTuses the small amount of light passing through the blind at fullclosure to give anaesthetic and restful effect in the room.

The foregoing and other objects and advan-` tages vof-fthe present invention will become. apparent tov those skilled in the art upon consideration of the following detailed description of the preferred embodiment thereof, reference being had to the accompanying drawing, wherein:

Figure 1 is aperspective View of a Venetian blind constructed in accordance with the principles of our invention; i

Figure 2 is a perspective View of one of the new typeslatafshowing the notches cut into one edge thereof;

Figure 3 is a sectional view through the blind taken at 3-3 in Figure 1;

Figure fl is aA sectionaliview taken at l-4 in Figure l, showing the `rnanner in which the slats contact one another when the blind is fully closed;

Figure 5 is a view similar to Figure 3, showing the blind in the open condition; and

`Figure 6 is a sectional view taken atv E-t in Figure 5.

In the drawings, the blind of Figure l is designated in its entirety by the reference numeral IB, and is seen to comprise a channel shaped head rail il, which. is supported at the ends by mounting brackets l2. Altilt rod I3 is rotatably supported within the head rail Il, and mounted on said rodnearpthe ends thereof are 'two Ytape rolls it, to which the upper ends oi ladders i5 are attached. Slats I6 are supported by the ladders in the usual manner.

Each oi the ladders l5 isY comprised of two parallel tapes 20 disposed on opposite sides of the slats IS and connected together by vertically spaced cross bars 2l which support the slats. The ladder illustrated in the drawings is formed of plastic, although any other material will serve equally well. y l

The cross bars 2l are somewhat less than half the width 'of the tapes 20, and are staggered-alternately on opposite sides of the centerline of the tapes, as shown in Figure 6. The inner edges of the staggered cross bars are spaced apart to provide a clear openingV 22 at the center of the ladder, and extending down through this openin'g'is a lift cord 23; The lift cord also extends throughf`transversely elongated cord holes 24 in each ofthe slats; said cord holes being preferably offset laterally to onegside of the centerline of the slat, as in Figure 6.

Each of the slats I6 is formed of crowned strip metal or other thin sheet material, and the slats are assembled in the ladders with the concave side facing downwardly, as shown in Figure 5. Formed in one edge of the slat in lateral alignment with the cord holes 24 are notches 25. The notches 25 are preferably wider than the overall distance between the outer edges of the staggered cross bars 2l, and are substantially deeper than the thickness of the lift cords 23. In the preferred form illustrated, the notch 25 is approximately 20% of the total width of the lslat I6, although it will be understood that the depth could be greater or less than the amount shown.

When the slats are assembled in the ladders I5, the cross bars 2i are engaged by the bottom of the notches 25 and by the edge of the slat on the opposite side thereof. With the blind open, the

slats I6 function in the same manner as in conventional blinds. When the blind of the present invention is fully closed, however, the slats I6 tilt almost to the vertical position, as shown in Figures 3 and 4, with the slats overlapping slightly and in contact with one another. This full closure of the blind is made possible by the notches 25, which eliminate the interference of the lift cord 23 with the slats.

AS mentioned earlier, with conventional blinds the crowned sheet metal slats are prevented from closing tightly together by the lift cords, which pass between the vertically tilted slats. The minimum gap between the bottom edge of each slat and the top surface of the slat below is therefore never less than the diameter of the cord, which is usually from 1A; to 1% inch. When the slat is notched at 25, a small opening is provided behind the ladder tape 20, through which the lift cord can pass without spreading the slats apart, and on either side of the notch, the bottom edge of the slat extends down to and abuts against the slat below, closing the gap between slats.

It will also be noted that when the blind is closed, each of the slats drops down slightly toward the slat below. This is because of the fact that the notch 25 is wider than the cross bars and therefore the slat is supported by the cross bar on the bottom of the notch. When the blind is open and the slats are horizontal, as in Figure 5, the slats are centered between the tapes 20. In the tilted position, the slat is supported entirely on its bottom edge, and therefore, drops down until the bottom edge of the notch 25 rests on the cross bar at the junction of the latter with the tape 20. The lateral oifset of the cord hole 24 also provides clearance for the lift cord 2l so that the slat can drop down without interference.

The effectiveness of the invention in darkening rooms for projection purposes has been clearly demonstrated in Vexperimental installations in classrooms of modern design having large windows on the north side thereof and smaller windows, set high, on the south side. It was found that the unshaded windows gave light meter readings, taken at student eye level, ranging from 60 to 180 foot-candles. The outside meter reading at the Sametime was 500 foot-candles at student eye level. With blinds tilted slightly, a more uniform light distribution was obtained, giving meter readings ranging from 50 to 90 footcandles. When fully closed,` blinds of pastel green gave meter readings of .25 to .54 foot-candles, whereas blinds of dark green gave meter readings of .11 to .32 foot-candles, all readings being taken at student eye level. It has been found that colored projection is entirely satisfactory and suffers no loss of color with a light intensity in the room of not more than 1/2 footcandle. A conventional Venetian blind of the same color passes fully 10 times as much light as the present blind when fully closed, and is entirely incapable of reducing the light intensity to the level required for satisfactory color projection.

While we have shown and described in detail what we believe to be the preferred form of our invention, it will be understood that various changes may be made in the shape and arrangement of the several elements thereof, without departing from the broad scope of the invention as defined in the appended claims.

W e claim:

1. A crowned slat for use in a full-closure Venetian blind having slat-supporting ladders and lift cords, each of said ladders comprising a pair of tapes disposed on opposite sides of said slats and connected together by a plurality of narrow cross bars which are staggered alternately on opposite sides of the centerline of the tapes, said lift co-rd passing down through said ladders between said alternately staggered cross bars, each of said slats being provided with a transversely elongated, closed cord hole offset laterally to one side of the longitudinal centerline thereof, said lift cords passing through said cord holes, and each of said slats having a longitudinally elongated notch formed in the edge thereof in lateral alignment with said cord hole on the opposite side of said centerline, said notch being wider than the combined width of two adjacent cross bars and substantially deeper than the thickness of said lift cord, and said notch being normally at the bottom of said slat when the latter is tilted to the closed position.

2. A full-closure Venetian blind comprising a plurality of horizontally extending, vertically spaced slats, at least two ladders supporting said slats, each of said ladders comprising a pair of tapes disposed on opposite sides of said slats and connected together by a plurality of vertically spaced narrow lcross bars staggered on opposite sides of the centerline of the tapes, lift cords passing down through said ladders between said alternately staggered cross bars, each of said slats being crowned and having transversely elongated, closed cord holes provided therein offset laterally to one side of the longitudinal centerline of the slat, said lift cords passing through said cord holes, and each of said slats having a longitudinally elongated notch formed in the edge thereof in lateral alignment with said cord hole on the opposite side of said centerline, said notch being wider than the combined width of two adjacent cross bars and substantially deepei` than the thickness of said lift cord, and said notch being normally at the bottom of said slat when the blind is tilted to closed position, whereby each slat drops the depth of said notches so that the bottom edge of the slat abuts against the top surface of the slat below.

LEON R. BCHER. OMAR K. SKIVER.

Name Date lJones Jan. 31, 1950 Number 

